Activated Carbon as an Electron Acceptor and Redox Mediator during the Anaerobic Biotransformation of Azo Dyes

F.P. van der Zee, I.A.E. Bisschops, G. Lettinga, J.A. Field

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223 Citations (Scopus)

Abstract

The role of AC as redox mediator in accelerating the reductive transformation of pollutants as well as a terminal electron acceptor in the biological oxidation of an organic substrate is described. This study explores the use of AC as an immobilized redox mediator for the reduction of a recalcitrant azo dye in laboratory-scale anaerobic bioreactors, using volatile fatty acids as electron donor
Activated carbon (AC) has a long history of applications in environmental technology as an adsorbent of pollutants for the purification of drinking waters and wastewaters. Here we describe novel role of AC as redox mediator in accelerating the reductive transformation of pollutants as well as a terminal electron acceptor in the biological oxidation of an organic substrate. This study explores the use of AC as an immobilized redox mediator for the reduction of a recalcitrant azo dye (hydrolyzed Reactive Red 2) in laboratory-scale anaerobic bioreactors, using volatile fatty acids as electron donor. The incorporation of AC in the sludge bed greatly improved dye removal and formation of aniline, a dye reduction product. These results indicate that AC acts as a redox mediator. In supporting batch experiments, bacteria were shown to oxidize acetate at the expense of reducing AC. Furthermore, AC greatly accelerated the chemical reduction of an azo dye by sulfide. The results taken as a whole clearly suggest that AC accepts electrons from the microbial oxidation of organic acids and transfers the electrons to azo dyes, accelerating their reduction. A possible role of quinone surface groups in the catalysis is discussed.
Original languageEnglish
Pages (from-to)402-408
JournalEnvironmental Science and Technology
Volume37
Issue number2
DOIs
Publication statusPublished - 2003

Keywords

  • sludges
  • carbon
  • redox reactions
  • pollutants
  • azo compounds
  • dyes
  • anaerobic treatment
  • oxidation
  • waste water treatment
  • sp strain bn6
  • oxidative dehydrogenation
  • catalytic-oxidation
  • hydrogen-sulfide
  • fluidized-bed
  • reduction
  • sludge
  • decolorization
  • degradation
  • quinones

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